1. Field of the Invention
The present invention relates generally to a method and system for the recovery of concrete. In particular, the invention relates to a method and system for the recovery of unused concrete material in a concrete slurry in a relatively efficient and effective manner.
2. Background Art
It is to be understood that there is no intention of an admission that any of the background art discussed in this section legally constitutes prior art.
Concrete is frequently delivered to a construction site in a concrete mixer truck. The truck has a rotating drum in which the components of concrete are mixed en route to the site. At the site, the concrete is poured from the drum onto a surface through a chute, which is typically part of the mixer truck. Once the delivery of the concrete is complete, however, the chute and other components may be coated with residual concrete material. This residual concrete material should, in many instances, be cleaned off of the chute and any other components in order to prevent hardening of the concrete in place on the components.
In cleaning the chute and other components, the runoff of the cleaning process shall be controlled for at least some applications. For example, it is desirable to prevent or limit the runoff from merely running onto the ground as the runoff materials may constitute a serious environmental hazard. Further, the runoff materials may constitute lost resources to the concrete provider.
One approach to recover concrete materials employ the use of a pressurizable tank which could be mounted on board a concrete mixer truck so that the runoff materials could be collected in a suitable container such as a bucket and then transferred to the tank. A strainer or filter at the inlet would remove larger particulate materials from the runoff so that the remaining concrete slurry is then admitted to the tank. The tank would then be pressurized, and a discharge line from the tank would re-circulate the pressurized slurry back into the truck mixing tank to safely recover the cementitious materials.
While such a system is effective and relatively inexpensive to manufacture, it has been suggested that the use of the manually carried container could be difficult or even dangerous for the operator. Also, for some applications, the valves used in controlling the pressurizing and discharging of the fluids from the recovery tank could become clogged by the slurry materials. Furthermore, there has been a concern that it could be, in some instances, difficult to pressurize the tank, and thus the relatively lower pressure level would, in certain applications, preclude the discharging of the entire contents of the tank, and thus unwanted materials could remain therein, and the valve clogging concerns could become exacerbated. In an attempt to overcome these concerns, as disclosed in U.S. Pat. No. 6,155,277, which is incorporated herein by reference, a pump was mounted on board the concrete mixing truck to re-circulate the filtered cementitious runoff back into the mixing drum of the truck. However, such pumps are necessarily quite expensive, and bulky to mount on the truck. Also, the pump is a suction-type pump which could become damaged by cementitious debris, thereby running the risk of necessitating expensive repairs or replacements.
Other attempts at addressing the problem of concrete reclamation, have been proposed in U.S. Pat. Nos. 3,997,434; 4,154,671 and 5,778,910, each of which is incorporated herein by reference. However, all of these patented techniques disclose relatively expensive techniques for concrete reclamation.